Light projection apparatus



Feb. 5,1952 IR. E. GUN-[HER A n 2,584,697

LIGHT PROJECTION APPARATUS Filed Aug. 19. 195o A HEIGHT or PAnAoLlc fr, REI-LECTOR l ENGTH 0F TOP PLANE REI-'LECTOR IN VEN TOR.

Patented Feb. 5, 1952 UNITED STATES PATENT UFFICE 2,584,697 I LIGHT PROJECTION APPARATUS Roland E. Gunther', Newark, N. J. Application August 19,v 195o,'seria1N0. 180,333

2 Claims.

This invention relates to a light projecting ap- 5 paratus, and more particularly to an apparatus for collecting light rays emanating from a source, and so directing them that there results a well-e dened separation between illuminated and non- The invention is particularly adaptable for use as a vehicle headlight system.v

illuminated areas.

It is an object of the present invention to pron vide a light projecting apparatus for vehicles, wherein adequate illumination is provided for driving while glare in the eyes of other operators is eliminated.

It is a further object to provide an improved arrangement of filament and reflectors for directing light in the manner described. y

The objects and advantages of this invention Fig. 1 is a side view in section of the apparatus,v

yshowing in addition to the parts that would be -seen in this section, some of the light rays emitted from the source and the manner in which they are directed by the device.

' tricity to the filament 2.

Fig. 2 is the same view as in Fig. 1, but showing a different group of light rays.

Fig. 3 is a top view in section of the appa- 'ratus. f

IIn the drawing, and distinguished by reference' numerals, are shown, in Fig. 1 a parabolic plane reflector I, and in the focal point of parabolic -plane reflector I, a filament 2 in cross section.

The axis of the parabola to which reflector Iconforms is indicated by a line marked a. Positioned above and extending forwardly from the upper edge of parabolic plane reector I is a fiat plane reflector 2. Flat plane reflector 3 is parallel to the axis a of parabolic plane refiector I. Parabolic plane reflector I and top flat'plane reflector 3v are so inclined that a horizontal line drawn through the focus of parabolic plane reector' I, as illustrated by the broken line marked h, just touches the end of flat plane reflector 3 away from parabolic reflector I. Positioned opposite parabolic plane-reflector I and with its upper edge adjoining the forward edge of top plane reflector 3 isA a transparent member 4. Between lthe lower edge of transparent rnemloer 4 and the lower edge of parabolic plane reflector I, and joined to both is a non-reflecting panel 5. Shown also in Fig. 1 are two light rays 6 and 'l .representative of those rays emitted from filament l2 which are given direction by'means of refiection from the parabolic plane reflector I.

Shown in Fig. 2 of the drawing are the same -parts as jin Fig. 1 and in place of the group of light rays mentioned above, in Fig. 2 are shown a light ray 8 representative of the rays which, coming directly from the filament 2, strike the top flat plane reflector 3 and are directed then through the transparent member 4; and a light Vray 9 representing those rays which when emitted from the filament 2 pass in the space between top flat plane reector 3 and non-refiective panel 5 without touching either, to leave the device via transparent member 4.

In Fig, 3 is shown a top view of the device in section, and herein the parabolic plane reflector I vhas a straight section. Filament 2 is also shown, and namely as a straight line element horizontally placed, and attached to electrical leads I0 and II to permit the conduction of elec- The inner reective surface of parabolic plane reflector I is parallel to filament 2. Shown in this View are sides I2 and I3 of the device through which pass the leads I0 and II, and which, together with the transparent member 4 shown here and reflector I, as well as top plane refiector 3 and non-reflective panel 5 previously shown, all combine to form .a continuous enclosure.

. The parts of the device having been identified, Atherefollows a description of the characteristics and features, with appropriate references to the drawings, to show how the device directs the rays of light produced in it.

When the device. is installed in a vehicle and positioned with respect to the horizontal' as described, so that -the focal point of the parabolic plane reflector I and the forward end of fiat plane reflector 3 are 0n the samelevel, anda suitable current is passed through the filament 2 light will be emitted in all directions therefr-om. Those rays striking the parabolic surface of'refiector I are all reflected in such a manner .that they proceed parallel to the axis of the parabola. The axis being sloped downwardly with -respect to the' horizontal, the rays 6 and 'l will yhave the same downward slope, as will all others reflected from the parabolic reector. Since the .focal point, in which the filament 2 is located, is on the same level as the forward end of top plane Vreflector 3 theslope of reflector 3 will be given by the-ratio: one half the height of parabolic -plane reflector I to the length of top. fiat refiector 3. The points of measurement for both of these dimensions are indicated in Fig. l.

Headlights on automobiles are conventionally placed at a height of approximately 36 inches from the ground. This usage would be adhered majority of the light rays must drop less than y three feet in thirty feet of longitudinal travel for eicient operation. This means that the ratio of one half the height of parabolic plane reflector l to length of flat plane reflector 3 would be at least 1:10, or better put the ratio of parabolic reflector height to top reflector length would be at least 1:5. The preferred ratio, however,

the present invention, is the fact that in the past the source of light. that is, the incandescent filament, was fully visible to the opposing motorist. and with the high candle-power units in common use, the combination of inefficient reilective direction and unshielded direct view of the filament produced a blinding glare, while in the present device neither source of glare is present. Further, with the vpresent device there is no need to have a high beam and a low beam as in devices used previously. The high beam being the normal and glareless beam, motorists are no is much higher since at common driving vspeeds it is necessary to provide illumination much fur-ther ahead of. the vehicle. For the rays to be directed forwardly to a distance of 240 feet, for instance, the ratio of parabolic plane reflector height to top flat plane reflector length is 1:40 and it is in ranges of this and greater magnitudes of ratios that the device is used. The upper limit of ratios is set only by design restrictions imposed by suchfactors as maximum space actually availvable for the top reflector, and minimum distances allowable between an incandescent filament and a reflecting surface without the latter being impaired by the heat from the filament. The unique AAfeature found in this invention which is embodied -in the uncoiled filament extended in a straight line along the inner surface of the parabolic plane reflector', permits the latter distance t0 be reduced much more than would be possible in previous practice, since it spreads the heat along a .line instead of concentrating it at a point as is usually done in paraboloid reflecting devices.

Of the rays which are not directed by reflection from the parabolic plane reflector, there are those as shown in-Fig. 2, which, like light ray 8 move in such va manner as to strike and be reflected .from top'reflector 3. AUpon reflection they are directed more downwardly than the slope ofv rehector 3, and together with light rays that move initially more downwardly, such as typified by fray. 9 provide illumination in the area between the zone of maximum illumination created by the .parabolic reflector, and the vehicle. A small portion of the light emitted will be in the angle between lines h and a of Fig. 1 and directed more Aupwardly than the majority of the rays. The highest ray that can leave the device, travels along line h after being emitted from the filament 2. Line h being horizontal, this means that no rays project above the horizontal, and the device being below the eye-level of other operators, this device cannot produce glare.

` Previously used vehicle headlight equipment caused glare from two sources. One was the inefciency of reflection from the paraboloid reflectors used prior to this invention, due to the fact that a point source of light would be needed for full control of the reflected light, and the actual source could not be made small enough. The present device, as may be seen from the side sectional views, presents to the parabolic section the cross section of the filament, which is practically apoint source for the light. The other, and main disadvantage of previous equipment overcome by longer put at .the mercy of each other to change to a considerate low beam when approaching one another, nor is it any longer necessary to forfeit the ability to see ahead of the vehicle in consideration of the other motorist by switching to a less eflicient illumination.

In the execution of the device herein described, the reflectors are preferably constructed as rst surface mirrors to enable them to reflect e.- ciently at the very small angles of incidence involved in much of their function.

I claim:

l. In an apparatus for the projection of light, the combination with a parabolic plane reflector, and a straight line horizontal filament located in the focus of said parabolic plane reflector, of a flat plane reflector abutting against the upper edge of said parabolic plane reflector and extending forwardly therefrom in a direction parallel to the axis of said parabolic plane reflector, said parabolic plane reflector and adjoining said flat plane reflector .being inclined forwardly downward from the horizontal in sucha manner that the end away from said parabolic plane refiector of said ilat plane reilector is on the same level as the focus of said parabolic plane reflector, andv aitransparent member positioned opposite said parabolic plane reflector and adjoining and extending downwardly from the forwardmost edge of said fiat plane reflector, and a non-reflective panel extending from -the bottom edge of said parabolic plane reflector to the bottom edge of said transparent member, and 'side -panels placed against and joined to the left and right edges REFERENCES CITED The following references are of record in the file cf` this patent:

UNITED STATES PATENTS 

